One might think that addressing Death directly would be cause for a solemn or possibly frightening occasion. Yet the overall tone of Donne’s poem is strangely calm and informal. The most obvious marker of informality in the poem is the speaker’s use of “thou” to address Death rather than the more formal “you.” Additionally, consider the conversational quality of the language in the opening quatrain:

     Death, be not proud, though some have called thee
     Mighty and dreadful, for thou art not so;
     For those whom thou think'st thou dost overthrow
     Die not, poor Death, nor yet canst thou kill me.

Donne uses two simple techniques here to convey calm informality. First, he introduces commas within individual lines, creating short pauses (or caesuras) that contour the speaker’s sentences into natural cadences. Second, instead of forcing stops at the end of every line, he allows for the first and third lines to run over. In combination with the midline pauses, these instances of overflow (or enjambment) enhance the quatrain’s conversational sound. Additionally, the speaker’s meditative thought process endows the overall poem with measured quality. In the sonnet’s three quatrains, the speaker patiently works through examples of Death’s powerlessness, diminishing its power at every turn. At times the speaker even casually patronizes their addressee, as when they say in a pitying aside, “poor Death.” Adopting an implicit sense of superiority, the speaker addresses Death with self-assured calm.